Addns.pl is a self-contained DynDNS update client for DynDNS.org (and possibly others). It supports a variety of IP detection methods including external webcheck/router pages. It also supports multiple configurations and hostnames, smart abuse prevention, and custom/static/dynamic DNS, and can run as a daemon, commandline options only, or with a configuration file.

The Berkeley Internet Name Domain (BIND) implements an Internet name server for Unix operating systems. The BIND consists of a server (or `daemon') called `named' and a suite of associated tools and libraries.
A name server is a network service that enables clients to name resources or objects and share this information with other objects in the network via the Domain Name System (DNS).

tzoperlcc3 is a TZO.com Dynamic DNS client which
seemlessly integrates into the administration
interface in the Cobat Qube 3 Internet Appliance
server. This allows for Qube 3 users to use any
of TZO.com's DNS/domain services on a dynamic or
static IP address. The client also has an
auto-update feature which can be configured to
check for IP changes from once every minute to
once a day, and allows e-mailing to the user if
the address does change.

CoCaLoRes is a configurable tool to resolve IP numbers to hostnames like in Apache, Squid, or other logfiles. It is able to cache lookups in a file, and works by default as a drop-in replacement for Apache's logresolve.

CustomDNS is a modular DNS server written in Java. It's based on Brian Wellington's dnsjava pacakge, but it adds support for virtual hostnames, SQL databases, and dynamic client updates. You can use CustomDNS out-of-the-box as a clone of ml.org/dyndns.org, or you can use it to develop custom DNS applications.

Dents is a from-scratch implementation of the server side of the DNS protocol, sharing no code with any other project. Among its several features are compatibility with named, a modular driver system and an extensible control facility which allows the administrator to control the running server.